Lower development and support costs. (In theory.) If you can ship one build and it runs on every device you care about, that's a huge burden lifted. It's not t

Lower development and support costs. (In theory.) If you can ship one build and it runs on every device you care about, that's a huge burden lifted. It's not there yet for all types of games or applications, for a number of reasons, but the performance aspect of it is gradually coming under control and most of the issue now rests on API functionality and browser compatibility.